Technical Field
This invention relates to the field of imaging devices. More particularly, the invention relates to methods and devices for capturing information for authentication of the imaging device operator.
Description of the Prior Art
In many situations, an ability to determine with certainty the details surrounding the creation of a photographic image is of great importance. Information such as the identity of the photographer and the date, time, and location of image creation may all lend credibility to images that are used in legal proceedings, scientific research, and other fields. The advent and wide distribution of computerized tools allowing for the duplication, modification, or outright falsification of images has heightened the importance of methods providing such authenticating information.
Several currently available technologies attempt to address these concerns.
For example, widely known are cameras that document the date and time of the image creation, storing this information either directly within the image or elsewhere on the film. The Kodak Advantix™ system allows cameras to record additional information on the film, such as image indexing and film processing instructions.
Other technologies have allowed the location of image creation to be documented.
The GPS DIG ITA system, developed by Kodak, allows the precise location of image creation, as determined by a Garmin GPS III Plus global positioning unit, to be recorded in the digital image captured by a Kodak DC265 camera.
Another aim of prior art technologies has been ensuring the integrity of a photograph following creation thereof. U.S. Pat. No. 5,499,294 discloses a digital camera that prevents modification or falsification of digital image content. “The digital camera processor has embedded therein a private key unique to it, and the camera housing has a public key that is so uniquely related to the private key that digital data encrypted with the private key may be decrypted using the public key.
The digital camera processor comprises means for calculating a hash of the image file using a predetermined algorithm, and second means for encrypting the image hash with the private key, thereby producing a digital signature. The image file and the digital signature are stored in suitable recording means so they will be available together. Apparatus for authenticating the image file as being free of any alteration uses the public key for decrypting the digital signature, thereby deriving a secure image hash identical to the image hash produced by the digital camera and used to produce the digital signature. The authenticating apparatus calculates from the image file an image hash using the same algorithm as before. By comparing this last image hash with the secure image hash, authenticity of the image file is determined if they match.”
U.S. Pat. No. 5,898,779 describes a similar system operating on only a portion of the digital image. “The encryption system further comprises means for generating one or more patterns each composed of at least one individual area that is visible together with the image of the object, means for designating at least one individual area as an active area of the image suitable for authentication and for generating location data identifying the active area, and means for calculating image hash from image data of the active area of the image using a predetermined hash algorithm. The image hash is then encrypted with the embedded private key, thereby producing a digital signature uniquely associated with the active area of the image.” The digital signature may then be used to verify the authenticity of the digital image as disclosed in U.S. Pat. No. 5,499,294, the use of only a selected portion of the image offering computational savings.
U.S. Pat. No. 6,005,936 discloses a method that obviates the need for recording a separate digital signature, embedding the authenticating information directly within the digital image. Specifically, the invention “divides the digital image into first and second regions. Authentication information is generated from data in the first region, which information is then encrypted. The encrypted authentication information is embedded into the second image region”. Finally, U.S. Pat. No. 6,111,954 discloses a steganographic method for recording authenticating information within an image stored on an emulsion film. “The marking encodes digital information, yet is essentially imperceptible to the human eye.”
However, none of these prior art technologies incorporate or record information in a manner providing reliable identification of the photographer. Thus, while the integrity of the image itself may be ensured, the identity of the photographer remains in question. Biometric identification technologies provide a convenient yet reliable approach to addressing this deficiency. Such technologies are both accurate, due to the unique nature of the physical traits use in the identification process, and reliable, due to the difficulty in falsifying such traits.
Several biometric identification techniques are currently available. Systems such as the Infineon FingerTIP™ and Biotouch Identix™ identify an individual based on fingerprint patterns. Such finger scanning systems analyze a fingerprint pattern to find distinctive minutiae, i.e. discontinuities that interrupt the ridge patterns of a fingerprint. The nature and location of the minutiae are noted, creating a record uniquely associated with the scanned fingerprint. Techniques have also been developed to identify individuals based on the shape and pattern of an entire hand.
There are also several technologies that identify a user based on the patterns within an individual's eye. Such eye sensors record and analyze patterns within the subject's iris or retina. Iris scanners, such as the IriScan™ system offered by Iridian, Inc., are both reliable and convenient. Retinal scanners such as the ICam 2001™ manufactured by EyeDentify, while more intrusive and typically requiring a more cooperative subject, offer unsurpassed reliability.
What is needed is an imaging device that provides a biometric mechanism for authenticating the photographer of an image. It would be advantageous to provide a device that uses biometric technology, thereby offering accurate and precise authentication.
United States patent application publication no. 2005/0036656 discloses a system in which a fingerprint scanner limits operation of a imaging device to registered users and incorporates the fingerprint information within the images using a digital watermarking process. Specifically, during an initial registration procedure, “the fingerprint information corresponding to the manager of the imaging device is recorded in the RAM.” The manager may, at his election, register additional operators. Then, prior to image acquisition, the operator of the imaging device is identified. The fingerprint scanner attains “the fingerprint of the thumb” and “a decision is made as to whether or not the detected fingerprint matches the fingerprint information belonging to any of the registrants.” If so, images may be acquired. For each image, “the ID information corresponding to the results of the fingerprint verification is read out from the ROM” and “undergoes the digital watermarking processing,” whereby it is “recorded in the photographed image.”
However, because there is a potentially substantial delay between the time of operator identification and the time of image capture, this approach provides only limited ability to authenticate the identity of the operator later at the time of image capture. Because a legitimate operator of the imaging device might misplace, have stolen, or otherwise lose custody of the imaging device after his identity is verified, there is little certainty that fingerprint information recorded in the photographed images is actually that of the legitimate operator.
It would be advantageous to provide a system that allows more reliable authentication of the operator of the imaging device at the time of image capture, i.e. the photographer who captured the image, at a time after an initial authentication or registration.
It would also be advantageous to provide a mechanism that ensures the integrity of the captured images, thereby preventing falsification or modification of the biometric information or image subsequent to capture and storage.
Finally, the device should be simple to use, with the authentication mechanisms functioning in a manner both convenient and unobtrusive to the photographer.